


Demon Bait

by riventhorn



Category: Ao no Exorcist | Blue Exorcist
Genre: Established Relationship, Future Fic, M/M, Rin and Bon are both Exorcists
Language: English
Status: Completed
Published: 2018-07-13
Updated: 2018-07-13
Packaged: 2019-05-27 23:31:51
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,692
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15035723
Author URL: https://archiveofourown.org/users/riventhorn/pseuds/riventhorn
Summary: In order to catch a gang of demons, Ryuuji has to be the bait.





	Demon Bait

**Author's Note:**

  * For [BridgetMcKennitt](https://archiveofourown.org/users/BridgetMcKennitt/gifts).



Ryuuji had never made a list of his least favorite places to be, but if he had, the abandoned warehouse he was currently being dragged into would have been near the top. Rusting pieces of machinery stood in the corners, and miasma oozed down the walls. He could see imps clustered in the deeper shadows, their red eyes unblinking. And he couldn’t forget his least favorite part—the metal table sitting in the middle of an intricate triangle drawn on the floor and scrawled with symbols denoting pain, blood, and sacrifice. Oh, and then there were the five demons standing around it and grinning at him.

He struggled uselessly with his bound hands. The gag tied over his mouth bit painfully into his skin and also kept him from invoking any prayers or sutras. His captor yanked him forward with the rope tied around his neck and clawed fingers dug into his chin. He found himself looking into blue, slitted eyes. 

“Don’t make this harder on yourself than it has to be,” Rin growled. 

“So you came through on your promise,” one of the demons standing by the table said to Rin. It flicked a forked tongue over its lips as it stared at Ryuuji. “You brought us an exorcist.”

“He will be a most suitable sacrifice,” one of the other demons commented, extending and retracting its claws. “I can smell his power from here. I’m impressed you were able to capture him.”

“Oh, it wasn’t so hard,” Rin murmured and for a second, his eyes grew less wild, the blue fire warmer. He was still facing Ryuuji, and so he let his mouth lift in a small smile. 

Ryuuji glared. Rin didn’t have to make him sound _weak_. And he’d tied the damn gag too tight. Sure, they had to make their act look realistic, but that didn’t mean going to extremes. 

Rin leaned closer, his mouth right by Ryuuji’s ear. “You doing okay?” he whispered, voice low and rough. “Usually _I’m_ the one tied up and gagged, after all.” And then the bastard licked Ryuuji’s ear. And was that—was that the sharp nick of his fangs? 

Was Rin treating their undercover mission as _foreplay_? Ryuuji was going to murder him. Right after he cuffed Rin to their bed and got back at him for the past few seconds. He knew exactly how much Rin liked _his_ tongue, after all. 

“So,” Rin said in a louder voice, turning away from Ryuuji and back to the demons. “Where’s your boss? I was promised a big reward for bringing in this sacrifice.”

That was the whole point of this charade—to smoke out the demon who was actually a threat. The five gathered here were nothing—he and Rin could have taken them out in five minutes without breaking a sweat. But after weeks of investigating, they hadn’t been able to locate the leader, who apparently wanted to sacrifice an exorcist in exchange for a boost in power before setting herself up as a mini-demon queen, gathering minions, wreaking chaos, etc., etc. So Rin infiltrated the gang and managed to strike a deal—bring them an exorcist in exchange for money and hopefully lure out the leader. 

Ryuuji hadn’t been exactly thrilled at the idea of being the bait, but Rin had gotten all serious, cupping Ryuuji’s face in his hands, and promising that he would never, ever let him get hurt. 

“I can look out for myself, dumbass,” Ryuuji had snapped, but then he leaned forward, tilting their foreheads together and covering Rin’s hands with their own. “Besides, I’m not worried—not really. We’re partners, right? I trust you to have my back.”

Even after all these years together, it still brought the same smile to Rin’s face as the first time Ryuuji said it to him. 

So no, Ryuuji wasn’t worried, but the fact that the demons’ boss wasn’t already here was a touch concerning. Especially when the demon with the forked tongue held up a briefcase, presumably full of cash, and said, through an unpleasant smile full of teeth, “We have your reward prepared. We’ll take things from here.”

Rin’s tail flicked back and forth, and Ryuuji hoped he was the only one who could tell it for the nervous gesture it was. Rin had tried to dress the part of a “hardcore demon bounty hunter” (Rin’s words), sporting a black leather jacket, knee-high combat boots, and a tight pair of jeans. He had slicked his hair up and had a fake tattoo creeping up the side of his neck. Frankly, Ryuuji felt he looked a bit ridiculous but hadn’t had the heart to say so when Rin looked so pleased with his ensemble. 

“Awww, come on,” Rin whined, slouching a little. “I want to stay for the fun part.”

“This is a sacred ritual,” one of the other demons hissed. “We do not want _interlopers_ among us.” 

But the forked-tongue demon held up a clawed hand. “When the ritual ends, our mistress will be looking for new servants.” It glanced at its companions. “This one captured an exorcist—he would be an asset in our ranks.”

 _Don’t sound too eager_ , Ryuuji directed silently at Rin. _Play it smoothly._

“I don’t know about joining you guys,” Rin said, poking idly at one of his fangs with his tongue. “Guess it depends on how strong your boss turns out to be. Still, if you let me watch the sacrifice, I might consider it.” 

The demons paused a moment, muttering amongst themselves. Then the forked-tongue demon stepped forward and gave Rin a short bow, its green eyes glowing. “Please, have a seat and enjoy the exorcist’s screams.”

And so, Ryuuji found himself strapped down to the metal table, shirt ripped away to bare his chest, gag still in place, while Rin lounged on a chair drinking a beer and chatting with a smaller demon, who had been silent up until now, about their favorite players on the Hanshin Tigers. 

“I’ve been trying to tempt their starting pitcher into selling his soul in exchange for a shutout game,” the demon was saying, “but he keeps insisting prayer will do the trick and with their record, I can’t exactly say he’s wrong.” 

Rin whistled. “Sounds tough. Hey, have you got any snacks around here?”

Ryuuji repeated a calming mantra in his head and tried to ignore the growing ache in his arms. 

After about half an hour of lying there, the forked-tongue demon appeared in his line of sight, a dagger held in one hand. At this concerning development, Ryuuji tensed and made a muffled noise.

A second later, Rin was there. “Whatcha doing?” he demanded of the demon. “I thought we were waiting for your boss to get here.”

The demon gave him a thin smile. “The ritual requires some preparation. We must remove the exorcist’s eyes and tongue. These will be burned separately while the sacrifice takes place.”

Well, shit. This was just getting better and better. 

Rin had put a hand on Ryuuji’s shoulder, and he clenched it reflexively, claws pricking Ryuuji’s skin. “I want to do it,” he said aloud. 

The demon scoffed, and Rin stamped his foot, like a petulant child. 

“It sounds like the best part,” he whined. “Come on, let me. It’s only fair, since I’m the one that captured him.”

The demon’s expression was remarkably similar to how Yukio used to look back at the Academy whenever he had to deal with Rin’s demands. 

“Very _well_ ,” it hissed, handing Rin the dagger. 

Rin made a big show of inspecting it, then complained that it was too dull and he needed to sharpen it. There was a limit to how long Rin could stall them, though. The demons were getting increasingly annoyed, and if only their boss would move her fucking ass and _get_ here, then—

Suddenly, the demons fell silent. Rin, who had been recounting an imaginary tale of the first time he cut out someone’s tongue, stuttered to a halt. Ryuuji raised his head as much as he was able and saw that the shadows in the back of the warehouse had grown thicker. The temperature was dropping too, and he shivered. 

The shadows swirled and then solidified into the shape of a woman. She wore a business suit, her hair tied back in a neat bun. She could have been one of the hundreds of women Ryuuji passed on the street. Except that her eyes were a flat, dead grey, and she stank of evil. 

The demons all bowed, and after a moment’s hesitation, so did Rin. 

“Is that my sacrifice, Belias?” she said, stepping closer and tucking a pair of sunglasses into her purse. “He smells delicious.”

The forked-tongue demon—Belias—remained crouched down, bobbing his head. “Yes, Mistress Lilith. It is an exorcist. I hope he is pleasing to you.”

“An exorcist?” She was standing next to Ryuuji now, and he couldn’t help shuddering when she put a hand on his chest, right over his heart. But her attention was already turning to Rin. “I assume we have you to thank for a sacrifice of such premium quality,” she said to him.

“That’s right,” Rin said, straightening up with a grin. “I’m the best bounty hunter in these parts. Always get my mark.” He shot off an imaginary pistol. 

Ryuuji made a mental note to forbid Rin from watching American western films right before a job. 

But Lilith laughed, a rich, throaty sound. “What a charming boy you’ve found for me, Belias.”

“He said he is interested in joining us,” Belias hastened to say, eager to take the credit.

“Your crew said I could watch the sacrifice,” Rin said, leaning against the table. “Thought I might stick around—if you want my talents.”

“A most tempting offer.” She drew closer to Rin. “Tell me, will you help slake my lusts when the ritual is complete?”

“Of course, mistress,” Rin said, his voice shaking a little. Ryuuji knew Rin could feel the darkness in Lilith too, an insidious cold that leeched the warmth from their fingers and slowed their hearts. 

“Excellent.” She drew back a step, and both of them sucked in a breath. “Now—I believe you were going to cut out the exorcist’s tongue. Proceed.”

“Right.” Rin bent over Ryuuji and their eyes met. It was time.

Rin slid the flat of the dagger blade across Ryuuji’s cheek, and then, with a quick movement, he cut through the gag and yanked it away. 

Ryuuji started chanting the second it was gone, invoking the spell that would summon Karura. 

“Traitor!” Belias shrieked, and Rin whirled and threw the dagger at Lilith’s heart. 

She plucked it out of the air as though it were a bothersome fly. Belias and another demon leapt at Rin, who snarled, blue fire sparking from his claws. 

But without Kurikara, he couldn’t harness the full extent of his power. And now Kurikara lived within Karura. 

That had been the deal he and Rin made with the Gregori, who, despite everything, had never completely trusted Rin. Ryuuji would shelter Kurikara with his familiar, Karura, and Rin would only be able to use the sword if Ryuuji summoned Karura first. 

Ryuuji hadn’t wanted to do it. He wasn’t Rin’s guard or watchdog, and he didn’t want to have that kind of power over him. But Rin begged him to do what the Gregori demanded. 

“Please, Ryuuji,” he had whispered. They had both been sitting on a bench, Rin leaning against him, his hair soft against Ryuuji’s cheek. “I’ve been fighting to be an exorcist for so long, and they won’t let me unless we do this. Please—I trust you.”

And he had agreed because he couldn’t refuse Rin’s begging, and some dark, possessive part of him had rejoiced at binding Rin that much closer to him.

But it meant that for a few seconds, until Karura appeared, they were vulnerable. Belias and the other demon bowled Rin over, and the three of them rolled away in a snarling, clawing mess. 

Still cuffed to the table, Ryuuji had his own problems. As the last syllables of the chant died on his lips, Lilith leapt onto the table, looming over him. Her eyes weren’t flat and dead anymore. A pale, unholy fire lit their depths. Dark scales started to sprout along her neck and arms. 

The sharp point of the dagger licked his ribs. And then flames burst in between them. Lilith fell backward with a shriek, and Ryuuji bit back a cry as the fire burned through the cuffs, scorching his skin. 

Karura spread its wings, the orange feathers tipped with a glowing crimson. It held Kurikara in its talons. 

“Ryuuji,” it said, and he could hear the note of disapproval in its voice. “You waited almost too long to call for me.”

“We had to wait for _her_ to arrive,” he said, pushing himself upright. The cut on his ribs was shallow but bleeding. He glared at Lilith, crouched on the floor and surrounded by the three remaining demons who weren’t attacking Rin. 

Speaking of— “Rin, catch!” he yelled, grabbing Kurikara and tossing it toward the tangle of bodies off to his right. 

Rin tore free long enough to catch the scabbard, and a second later, his blue fire intensified as he drew the sword. 

He didn’t look hurt, as far as Ryuuji could tell, but he could only spare him a glance. An ominous ripping noise pulled his attention back to Lilith, just in time to see her suit coat rip in half as two wings emerged from her back. 

With another shriek, she charged him. Karura swooped in between them, and Ryuuji pressed his hands together, fingers touching, focusing as Karura drew on his energy. Lilith swiped at Karura with one clawed arm, hissing as the flames burned her. She retreated once more. 

Damned if he’d stay on the defensive, though. He started chanting, and Karura, hearing and obeying his will, grew in size, towering up toward the ceiling and then speeding down toward the huddled demons, narrowing into a flaming spear. 

For a few moments, Ryuuji couldn’t see anything past the maelstrom of flames. He held it as long as he could, but finally he had to reduce the amount of energy Karura was drawing. His legs shook, and he put out a hand, steadying himself on the table.

Karura flew back to hover beside him. The firestorm had scorched the floor of the warehouse and all that remained of the demons was a pile of blackened bones and ashes. 

A gurgling cry came from behind him, and he turned to see Rin bury Kurikara in Belias’s heart. The other demon was already dead, crumpled on the floor.

Letting out a relieved breath, Ryuuji groped for the remains of his shirt, pressing it to the wound across his ribs. 

And then Rin’s voice broke the air, filled with desperate urgency. “Ryuuji—above you!”

He looked up and had a brief glimpse of Lilith dropping down from the ceiling, her lips curled into a snarl, all of her skin now covered in the dark, leathery scales, before her shadows enveloped him. 

He struck the floor hard. It was dark and cold, and time seemed to have slowed, each of his heartbeats labored with fear. Karura was still with him, though, and for a moment he pushed the shadows back. But Karura was no more than a tiny flame, flickering in the darkness, wavering as his strength and will ebbed. 

He couldn’t see Lilith, but her voice whispered to him, _I will eat your heart, exorcist._

God, she was powerful—more powerful than they had guessed. Her attacks up until now had been nothing, merely testing the waters. 

But if he went down, then Rin would be left alone to face her. Gritting his teeth, he fed more power into Karura. 

“Ryuuji, stop,” Karura said, looking at him with its solemn eyes. “You will extinguish your life’s energy if you continue.” 

“I don’t care,” he gasped. “We have to help Rin.” 

But it was so, so cold. Not the bracing cold of a winter day, but the damp, frigid chill that lurked in deep, underground places where the sun could never shine. All that was left of him could barely make Karura the size of a candle flame. His breath seized in his chest. 

_Rin… I’m sorry_ …

And then with a sudden rush of sound and light, the darkness lifted. He sucked in a breath, coughing violently, and rolled onto his side. He was still in the warehouse, not buried beneath the earth, and perhaps a second or two had passed, although it had seemed forever, locked in Lilith’s spell. 

Rin was fighting her. He was fully shifted into his demon form now, enveloped in blue fire, and wielding Kurikara. Ryuuji tried to stand, tried to go help, but it was too much, and he sagged back down, shaking. Karura hovered anxiously at his shoulder. 

“It’s all right,” he managed, and he held out his hand, cupping his familiar in his palm. Karura was still a tiny flame, but it would grow again. 

He could tell that he and Karura had weakened Lilith—one of her wings had been shredded, and the entire left side of her body looked as though it had half-melted. It didn’t take Rin long to finish her off. He severed her head in one long, clean swipe, and then let Kurikara fall to the ground, turning to run to Ryuuji.

Once, he would have been frightened of Rin like this, with his claws, fangs, and long ears. But now he surrendered easily to Rin’s touch, letting him gather him in his arms and hold him close.

*

Ryuuji insisted that he didn’t need to go to the hospital, and so as soon as they got home, Rin chivvied him into the bathroom so he could clean and dress the cut on his ribs and put salve on the reddened skin around his wrists. 

Ryuuji sat on the edge of the tub, looking down at Rin’s bent head as he tended to Ryuuji’s injuries. Rin’s brow was furrowed in concentration as he carefully wiped away the blood. Somehow, it always took Ryuuji by surprise, how Rin, who was so often loud and exuberant and rough, could be so gentle with him. 

Although usually after a mission like this, he’d be chattering about the fight and bragging about how cool they’d both been.

“You okay?” he asked, perturbed at Rin’s continued silence. 

Rin glanced up at him, then back down. “Yeah.”

“Don’t lie.” He brushed his fingers across the scrape decorating Rin’s left cheekbone. 

“That’s nothing.” Rin ducked away from his hand. “It’s nothing compared to—”

_Compared to what happened to you._

“Hey.” When Rin didn’t look at him, just kept taping down the bandage, Ryuuji caught his hands in his own, forcing him to stop. “Rin.”

Rin finally looked back up, his eyes shining with unshed tears. “I promised I wouldn’t let you get hurt! And you almost _died_.”

“But you saved me.” He let go of Rin’s hands and gripped his shoulders instead. “This job comes with risks—no, Rin, _listen_ to me. You think I expected to get out of that with nothing to show for it? Of course not. But what I did know? That you would do your damnedest to make sure we both walked out of there alive and made it home together. And we _did_. We did.”

Rin screwed his eyes shut, gulped a breath, and then leaned forward, thudding his head against Ryuuji’s chest, his arms closing around him. 

Ryuuji hid a wince and leaned down to kiss Rin’s dark hair. “Idiot,” he whispered. 

Rin’s arms tightened around him a second longer, and then he pulled back, smoothing his fingers across the bandage and sniffing. 

“You were a pretty awesome demon bounty hunter,” Ryuuji told him. 

A grin broke out on Rin’s face after a moment, growing stronger as he shook off the lingering fear and guilt. “I know! I looked so cool—too bad my leather jacket got ripped to shreds.” He sighed, and then focused on Ryuuji, his smile quirking into a smirk and his tail weaving a sinuous pattern in the air behind him. “You weren’t a bad sacrifice—laid out on that table—almost naked.” 

“I wasn’t almost naked,” he protested, face going hot, as Rin leaned up into his space, arms bracketing Ryuuji’s thighs. 

“You could be now,” Rin murmured, eyes dark. “I could lay you out on the bed, all trussed up for me.”

Ryuuji’s stomach jumped at the thought, but he shook his head, breathing going a bit shaky. “No way—not after lying there on that fucking table listening to you drink beer and chat about baseball. _You’re_ the one who’s gonna be tied down.”

“Yeah?” Rin rubbed against him, like a cat, and Ryuuji felt the wet flick of his tongue against his earlobe. 

“Yeah.” He started to stand up to make good on this promise, and as he did the whole world tilted. He staggered sideways, and then Rin was there, catching him before he slammed into the wall. 

Oh—guess he’d forgotten about the whole “almost draining his life’s energy to power Karura” thing. 

Rin chuckled. “Okay, so maybe we’ve both had enough for the day, huh? Change of plans—I’m going to cook us a big dinner, replenish all that energy you burned, and then I’m tucking you into bed to _sleep_.” 

“Well, tomorrow I’m getting what you owe me,” he muttered, deciding he probably shouldn’t try and argue the point when he could barely stand.

Rin’s arm went around his shoulders, helping him toward the kitchen. “Sure thing, Bon,” he murmured, the old, childish nickname slipping out, warm and soft. 

Usually he protested when Rin called him that, but it felt right tonight, a reminder of how they had always had each other’s backs and always would, partners in confronting the darkness and seeing each other through to the light on the other side.


End file.
